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Correct Answer: C
Correct Answer: C
Method / Topic: Physics
The correct option matches the required rule and the given information.
Short Explanation
Detailed Explanation
Correct Answer: C
Method / Topic: Physics
Poiseuille's law gives Q proportional to r⁴. The new radius is 0.80r, so Qnew/Qold = (0.80)⁴ = 0.4096, approximately 0.41. The fourth-power dependence makes a modest decrease in radius produce a large reduction in flow. This result follows from the stated physical model and consistent SI units. For MCAT physics, first identify the system, list known quantities, and choose the governing relationship before substituting numbers. Track direction, signs, exponents, and unit conversions; then test whether the magnitude is physically reasonable. Common distractors omit a round trip, confuse radius with area, ignore an inverse-square or fourth-power dependence, use peak instead of average behavior, or mix stored energy with dissipated power. In clinical and laboratory settings, the same
helps interpret imaging depth, fluid flow, electrical discharge, forces, and energy safely. A final dimensional check should reproduce the unit requested in the
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PASSAGE 2 — BLOOD FLOW MODEL A researcher models blood as an incompressible fluid flowing steadily through a horizontal artery. A section of radius 2.0 mm narrows to radius 1.0 mm. The volume flow rate is 4.0 × 10⁻⁶ m³/s. For a separate calculation, assume laminar flow obeys Poiseuille's law, Q = ΔPπr⁴/(8ηL). Blood density is 1000 kg/m³. QUESTION 6: If radius is reduced by 20% while ΔP, η, and L remain constant, the new laminar flow rate is approximately what fraction of the original rate?
Explanation
Correct Answer: C
Method / Topic: Physics
The correct option matches the required rule and the given information.
Short Explanation
Detailed Explanation
Correct Answer: C
Method / Topic: Physics
Poiseuille's law gives Q proportional to r⁴. The new radius is 0.80r, so Qnew/Qold = (0.80)⁴ = 0.4096, approximately 0.41. The fourth-power dependence makes a modest decrease in radius produce a large reduction in flow. This result follows from the stated physical model and consistent SI units. For MCAT physics, first identify the system, list known quantities, and choose the governing relationship before substituting numbers. Track direction, signs, exponents, and unit conversions; then test whether the magnitude is physically reasonable. Common distractors omit a round trip, confuse radius with area, ignore an inverse-square or fourth-power dependence, use peak instead of average behavior, or mix stored energy with dissipated power. In clinical and laboratory settings, the same
helps interpret imaging depth, fluid flow, electrical discharge, forces, and energy safely. A final dimensional check should reproduce the unit requested in the
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